Last week you and a friend went to an electronics store. you purchased a television for $600 and your friend bought a video game for $40. today you saw in the newspaper that the electronics store was having a huge sale and your television is now $580 and your friend's game is $20. you decide it is not worth it for you to go and get a price change, but you call your friend because you cannot think of a reason why he/she would not want to go and get a price adjustment. the potential savings for you and your friend is exactly the same so why might you assume your friend would want a price adjustment when you did not?

Reliability and validity reliability and validity are two important considerations that must be made with any type of data collection. reliability refers to the ability to consistently produce a given result. in the context of psychological research, this would mean that any instruments or tools used to collect data do so in consistent, reproducible ways. unfortunately, being consistent in measurement does not necessarily mean that you have measured something correctly. to illustrate this concept, consider a kitchen scale that would be used to measure the weight of cereal that you eat in the morning. if the scale is not properly calibrated, it may consistently under- or overestimate the amount of cereal that’s being measured. while the scale is highly reliable in producing consistent results (e.g., the same amount of cereal poured onto the scale produces the same reading each time), those results are incorrect. this is where validity comes into play. validity refers to the extent to which a given instrument or tool accurately measures what it’s supposed to measure. while any valid measure is by necessity reliable, the reverse is not necessarily true. researchers strive to use instruments that are both highly reliable and valid.